Methods and instrument for vertebral interbody fusion

ABSTRACT

Methods and instrumentation particularly adapted for disc space preparation for insertion of implants from an anterior approach to the spine are provided. The instruments include a guide sleeve defining a channel having overlapping cylindrical working channel portions and lateral non-distracting extensions extending from reduced thickness wall portions. The guide sleeve has an overall reduced width configuration. A pair of distractors are provided. A first distractor includes a shaft and distal tip, each having convex walls. A second distractor includes a shaft and distal tip including a recessed area at least along the tip. The first distractor is at least partially received within the recessed area of the second distractor when the first and second distractors are in side-by-side relation and a reduced overall width of the distractors is obtained. Preferably, the first and second distractors are used with the guide sleeve. Methods using the disclosed instruments are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 10/631,241 filed on Jul. 31, 2003, now U.S. Pat.No. 7,244,258 which is a divisional application of U.S. patentapplication Ser. No. 09/756,492 filed on Jan. 8, 2001 and now issued asU.S. Pat. No. 6,648,895; which is a continuation-in-part of U.S. patentapplication Ser. No. 09/498,426, filed Feb. 4, 2000, and now issued asU.S. Pat. No. 6,575,981; which claims the benefit of the filing date ofU.S. Provisional Application Ser. No. 60/118,793, filed on Feb. 4, 1999,each of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to surgical procedures forspinal stabilization and more specifically to instrumentation adaptedfor inserting a spinal implant within the intervertebral disc spacebetween adjacent vertebra. More particularly, while aspects of theinvention may have other applications, the present invention isespecially suited for disc space preparation and implant insertion intoa disc space from an anterior surgical approach to the spine.

Various surgical methods have been devised for the implantation offusion devices into the disc space. Both anterior and posterior surgicalapproaches have been used for interbody fusions. In 1956, Ralph Clowarddeveloped a method and instrumentation for anterior spinal interbodyfusion of the cervical spine. Cloward surgically removed the discmaterial and placed a tubular drill guide with a large foot plate andprongs over an alignment rod and then embedded the prongs into adjacentvertebrae. The drill guide served to maintain the alignment of thevertebrae and facilitated the reaming out of bone material adjacent thedisc space. The reaming process created a bore to accommodate a bonedowel implant. The drill guide was thereafter removed following thereaming process to allow for the passage of the bone dowel which had anouter diameter significantly larger than the reamed bore and the innerdiameter of the drill guide. The removal of the drill guide left thedowel insertion phase completely unprotected.

More recent techniques have advanced this concept and have providedfurther protection for sensitive tissue during disc space preparationand dowel insertion. Such techniques have been applied to an anteriorapproach to the lumbar spine.

An initial opening or openings are made in the disc space and the heightof the disc space is distracted to approximate normal height. Typically,a first distractor is inserted with a height estimated by radiologicalexamination. If additional distraction is required, the first distractoris removed and a second, larger distractor is inserted. However, sincethe positioning of the distractors is performed without the benefit ofprotective guide sleeves, the switching of distractors increases thepotential for damage to neurovascular structures and may correspondinglyincrease the time of the procedure.

For bilateral procedures, a double barrel sleeve may be inserted overthe distractors, with a central extension extending into the disc spaceto maintain distraction. One limitation on guide sleeve placement is theamount of neurovascular retraction that must be achieved to place theguide sleeves against the disc space. For some patients, a double barrelsleeve may not be used because there is insufficient space adjacent thedisc space to accept the sleeve assembly. Thus, there remains a need forguide sleeves requiring less neurovascular retraction for properplacement and providing greater protection to adjacent tissue.

While the above-described techniques are advances, improvement is stillneeded to reduce the procedure time by utilization of improvedinstruments and techniques, to reduce the potential for damage tosensitive tissue adjacent the disc space, and to limit the amount ofvessel retraction necessary to utilize the protective instrumentation.The present invention is directed to this need and provides moreeffective methods and instrumentation for achieving the same.

SUMMARY OF THE INVENTION

The present invention relates to methods and instrumentation forvertebral interbody fusion. In one aspect of the invention, theinstruments define a reduced width configuration that allows bilateralinsertion of cylindrical and tapered implants into the disc space.

In another aspect of the invention, a surgical instrument assembly fordistracting a spinal disc space is provided. The assembly includes afirst distractor that has a first shaft extending between a proximal endand a distal end and a first distractor tip defining a distractionheight that extends from the distal end of the first shaft. The firstdistractor also has a projection extending from a medial side of theshaft. The assembly further includes a second distractor having a secondshaft extending between a proximal end and a distal end and a seconddistractor tip extending defining a distraction height. The seconddistractor also has a notch formed in a medial side of the second shaft.The assembly also includes a guide sleeve having a working channelextending between a proximal end and a distal end the sleeve. The firstand second distractors are received in the working channel of the guidesleeve with the projection positioned in the notch. The proximal end ofthe first and second distractors and the guide sleeve are coupled to adistractor driver cap that has a side opening that allows the distractordriver cap to be side-loaded onto the proximal ends of the first andsecond distractors and the guide sleeve.

In another aspect of the present invention, a method for preparing aspinal disc space between a pair of vertebral endplates for insertion ofan implant therebetween is provided. The method includes inserting aguide sleeve to the disc space from an anterior approach, the guidesleeve having a working channel providing access to a first disc spacelocation and a second disc space location; distracting the disc space toa desired disc space height; preparing the first disc space locationthrough the working channel for insertion of a first implant therein;inserting a reamer plug through the working channel into the first discspace location; preparing the second disc space location through theworking channel for insertion of a second implant therein afterinserting the reamer plug; inserting the second implant through theworking channel into the second disc space location, the second implantbeing tapered to establish a desired lordotic angle between thevertebral endplates; removing the plug from the first disc spacelocation after inserting the second implant; and inserting the firstimplant through the working channel into the first disc space location,the first implant being tapered to establish a desired lordotic anglebetween the vertebral endplates.

In a further aspect of the invention, an implant inserter is provided.The implant inserter includes an implant holder engageable to an implantthat is biased to the disengaged position. The implant holder isthreadingly engaged in the hollow interior of a driver sleeve. Thedriver sleeve has a plastic bushing on its distal end that contacts atapered portion of the implant holder to move the implant holder to theengaged position with the implant.

Related objects, advantages, aspects, forms, and features of the presentinvention will be apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is a perspective view of a distractor according to the presentinvention.

FIG. 1 b is an enlarged front view of the tip of the distractor of FIG.1 a.

FIG. 1 c is an enlarged side view of the tip of the distractor of FIG. 1a.

FIG. 2 a is a perspective view of a distractor according to anotheraspect of the present invention.

FIG. 2 b is an enlarged front view of the tip of the distractor of FIG.2 a.

FIG. 2 c is an enlarged side view of the tip of the distractor of FIG. 2a.

FIG. 2 d is an elevation view of a distractor clip.

FIG. 3 is a perspective view of a guide sleeve according to anotheraspect of the present invention.

FIG. 4 is a front view of the guide sleeve of FIG. 3.

FIG. 5 is a side view of the guide sleeve of FIG. 3.

FIG. 6 is a perspective view of a guide sleeve assembly according toanother aspect of the present invention.

FIG. 7 is an enlarged end view of the distal end of the guide sleeveassembly of FIG. 6.

FIG. 8 is an enlarged end view of the proximal end of the guide sleeveassembly of FIG. 6.

FIG. 9 is an anterior to posterior view of a guide sleeve assemblyaccording to FIG. 3, the guide sleeve assembly is positioned in relationto a pair of adjacent vertebral bodies and blood vessels.

FIG. 10 is a partial cross-sectional view of the disc space through line10-10 of FIG. 9.

FIG. 11 is a perspective view of the guide sleeve assembly duringinsertion of the distractors into the disc space.

FIGS. 11 a and 11 b are front and rear elevation views, respectively, ofa distractor driver cap for driving the distractors into the disc space.

FIGS. 12 a-12 b are perspective views of the guide sleeve assembly 150with an impactor cap disposed thereon prior to seating the guide sleeve.

FIG. 13 is a perspective view of the guide sleeve assembly with animpactor cap disposed thereon.

FIG. 14 is a perspective view of the guide sleeve assembly with a slaphammer disposed on one of the distractors.

FIGS. 15 a-15 b are a perspective view and an end view, respectively, ofthe guide sleeve assembly with a distractor removed.

FIGS. 16 a-16 b are a perspective view and an end view, respectively, ofthe guide sleeve assembly with a reamer disposed adjacent a distractor.

FIGS. 17 a-17 c are a perspective view, detail view and end view,respectively, of the guide sleeve assembly with a tap disposed adjacenta distractor.

FIGS. 18 a-18 c are a perspective view, detail view and end view,respectively, of the guide sleeve assembly with an implant disposedadjacent a distractor.

FIGS. 19 a-19 c are perspective views and an end view, respectively, ofthe guide sleeve assembly showing withdrawal of the other distractor.

FIGS. 20 a-20 b are a perspective view and an end view, respectively, ofthe guide sleeve assembly with a reamer disposed adjacent an implant.

FIGS. 21 a-21 c are a perspective view, detail view and end view,respectively, of the guide sleeve assembly with a tap disposed adjacentan implant.

FIGS. 22 a-22 c are a perspective view, detail view and end view,respectively, of the guide sleeve assembly with an implant disposedadjacent an implant.

FIG. 23 a is an elevational view of another embodiment first distractoraccording to the present invention.

FIG. 23 b is an elevational view of the distractor of FIG. 23 a rotated90 degrees about its longitudinal axis.

FIG. 23 c is a right end view of the distractor of FIG. 23 b.

FIG. 24 a is an elevational view of another embodiment second distractoraccording to the present invention.

FIG. 24 b is an elevational view of the distractor of FIG. 24 a rotated90 degrees about its longitudinal axis.

FIG. 24 c is a right end view of the distractor of FIG. 24 b.

FIGS. 25 a and 25 b show the assembly of the distractors of FIGS. 23 a-cand FIGS. 24 a-c in side-by-side relation.

FIG. 26 a is an elevational view another embodiment guide sleeveaccording to the present invention.

FIG. 26 b is an elevational view in partial section of the guide sleeveof FIG. 26 a rotated 90 degrees about its longitudinal axis.

FIG. 26 c is a left end view of the guide sleeve of FIG. 26 b.

FIGS. 27 a and 27 b are a top perspective view and a bottom perspectiveview of a distractor driver cap according to a further aspect of thepresent invention.

FIG. 27 c is a cross-sectional view taken through line 27 c-27 c of FIG.27 a.

FIG. 27 d is a left end elevational view of the distractor driver cap ofFIG. 27 a.

FIG. 28 shows a distractor assembly secured to the distractor driver capof FIGS. 27 a-27 d.

FIG. 29 is an elevational view of a reamer having application in thepresent invention.

FIG. 30 a is an elevational view of reamer plug according to anotheraspect of the present invention.

FIG. 30 b is a left end view of the reamer plug of FIG. 30 a.

FIG. 31 is an elevational view of an implant adjuster having applicationin the present invention.

FIG. 32 a is an elevational view of an implant holder according to thepresent invention.

FIG. 32 b is an elevational view of the implant holder of FIG. 32 arotated 90 degrees about its longitudinal axis.

FIG. 33 is an elevational view of an outer sleeve for receiving theimplant holder of FIG. 32 a.

FIG. 34 is a perspective view of a wrench usable with the outer sleeveand implant holder shaft of FIGS. 33 and 32 a, respectively.

FIGS. 35 a-35 c illustrate various steps in locating and marking themidline of the disc space at a subject vertebral level.

FIGS. 36 a-36 c illustrate various steps in performing a discectomy atthe subject vertebral level.

FIG. 37 is a perspective view of a starter distractor set with varioussized distractor tips for use therewith.

FIG. 38 illustrates insertion of a distractor/guide sleeve assembly intothe disc space with the distractor driver cap of FIGS. 27 a-27 d securedthereto.

FIG. 39 illustrates insertion of the guide sleeve into the disc spaceusing an impactor cap.

FIGS. 40 a-40 c illustrate removal of a first distractor from the guidesleeve after insertion of the distractor/guide sleeve assembly into thedisc space.

FIGS. 41 a-41 b illustrate reaming a first implant insertion location inthe disc space through the guide sleeve.

FIGS. 42 a-42 b illustrate insertion of a reamer plug in the reamedfirst implant insertion location and reaming a second implant insertionlocation in the disc space through the guide sleeve.

FIGS. 43 a-43 b illustrate securement of an implant to the implantholder of FIG. 32 a using the driver sleeve.

FIGS. 44 a-44 c illustrate insertion of the implant into the secondimplant insertion location in the disc space through the guide sleeve.

FIG. 45 illustrates implants inserted into the disc space at the firstimplant location and the second implant location.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, such alterations and furthermodifications in the illustrated device, and such further applicationsof the principles of the invention as illustrated therein beingcontemplated as would normally occur to one skilled in the art to whichthe invention relates.

The present invention relates to methods and instrumentation forperforming vertebral interbody fusion. Specifically, although aspects ofthe present invention may have other uses either alone or incombination, the instruments and methods disclosed herein areparticularly useful for anterior lumbar interbody fusion. However, thesurgical instruments and methods according to the present invention arenot limited to such an approach, and may find application in, butwithout limitation, lateral and anterior-lateral approaches to the spineas well. Also, the surgical instruments and methods of the presentinvention may find application at all vertebral segments of the spine,and in areas other than spinal surgery.

Referring now to FIGS. 1 a-c, there is shown a convex or first discspace distractor 50 according to one aspect of the present invention.Distractor 50 includes a proximal end 53 configured for engagement withconventional tools and handles (not shown) used in operative procedureson the spine. A shaft 54 is joined with a distractor tip 56. In theillustrated embodiment, shaft 54 has a hollow interior and a clip hole55 communicating with the hollow interior; however, the presentinvention also contemplates a solid shaft 54. Also, while an integralshaft and head are shown, head 56 may be removably attached to shaft 54.One such removable attachment is more fully disclosed in U.S. patentapplication entitled METHOD AND INSTRUMENTATION FOR VERTEBRAL INTERBODYFUSION, Ser. No. 09/287,917, filed Apr. 7, 1999, which is incorporatedherein by reference in its entirety (hereinafter referred to as the '917patent application.) Distractor tip 56 is designed such that it can beinserted in a disc space to establish a first working distraction height72 (see FIG. 1 b). More specifically, distractor tip 56 has a roundedleading edge 62 that extends to opposing inclined surfaces 58 and 59,which in turn extend more proximally and blend into substantially planaropposing surfaces 60 and 61, respectively. Extending between planarsurfaces 60 and 61 and proximal the rounded tip 62 are opposite convexsurfaces 64 and 66.

Planar surfaces 60 and 61 extend in a substantially parallel alignmentalong a longitudinal axis A of distractor 50 and define height 72therebetween. It should be understood that the inclined surfaces 58 and59 cooperate to aid insertion of the distractor tip 56 into the discspace and to initially distract the disc space to at least a height 72.If first distraction height 72 is sufficient, further procedures asknown in the art may then be carried out to accomplish implantinsertion. While a specific distractor has been described in detail, itis contemplated that other known distractor configurations may besubstituted for the same without deviating from the scope of thisinvention.

Referring now to FIGS. 2 a-c, there is shown a second disc spacedistractor 80 according to one aspect of the present invention.Distractor 80 includes a proximal end 83 configured for engagement withconventional tools and handles (not shown). A shaft 84 is joined with adistractor tip 86. In the illustrated embodiment, shaft 84 has a hollowinterior and a hole 85 communicating therewith. While an integral shaftand head are shown, head 86 may be removably attached to shaft 84, assimilarly described with respect to the removable attachments disclosedin the '917 patent application. Similar to distractor tip 56 ofdistractor 50, distractor tip 86 is designed such that it can beinserted in a disc space to establish a first working distraction height72′ (see FIG. 2 b) that is preferably the substantially the same asworking height 72. More specifically, distractor tip 86 has a roundedleading edge 92 that extends to opposing inclined surfaces 88 and 89which, in turn, extend more proximally and blend into substantiallyplanar opposing surfaces 90 and 91, respectively.

Planar surfaces 90 and 91 extend substantially parallel to longitudinalaxis B of distractor 80 to define height 72′ therebetween. Extendingbetween planar surfaces 90 and 91 are convex surface 94 and a recessedarea defined by opposite concave surface 96. Along the distractor shaft84, there is defined a concave surface 98 that is adjacent to andcoplanar with concave surface 96 of distal tip 86 to define a concavesurface extending along the length of distractor 80. In the illustratedembodiment, surface 98 has a slot 87 formed therein communicating withthe hollow interior of shaft 84; however, it the present invention alsocontemplates a solid shaft 84 and a shaft 84 without slot 87. Asexplained more fully below, concave surfaces 96, 98 are configured toreceive convex surface 64 or 66 of distractor 50 to reside therein whendistractors 50 and 80 are disposed in side-by-side relation. Concavesurfaces 96, 98 also partially define a working space that allowsoperative procedures to be performed therethrough.

It should be understood that the inclined surfaces 88 and 89 cooperateto aid insertion of distractor tip 86 into the disc space, and todistract the disc space and maintain disc space distraction to at leasta height 72, 72′. To further aid in distractor insertion, in FIG. 2 dthere is shown a distractor clip 75 having a cross member 76 with firstclip member 77 and second clip member 78 extending therefrom. Clipmembers 77 and 78 are each received in a corresponding one of holes 55and 85 to couple distractor 50 to distractor 80. Clip 75 preventssplaying and maintains the relative positioning of distractors 50, 80during insertion into the disc space. If first distraction height 72 issufficient, further procedures as known in the art may then be carriedout to accomplish implant insertion. It should be further understoodthat second distractor 80 has a second width 74 that is less than afirst width 70 of first distractor 50.

Specifically, but without limitation, the distractor heads 56, 86 may beformed with heights 72 ranging from 6 mm to 24 mm. Preferably, height 72of the next sized distractor increases or decreases in 2 mm increments.Other variations and may be provided as long as the working distractorheight provided approximates the disc height in a normal spine andaccommodates insertion of an implant into the disc space as more fullydescribed below.

Referring now to FIG. 3, there is shown a guide sleeve 100 that isuseful with the distractors 50 and 80 described above. Guide sleeve 100has a wall 110 defining a working channel 130 having a figure eightshaped cross-section (FIG. 9) extending in a substantially unobstructedmanner from a proximal end 102 to a distal end 104. Sleeve 100 includesupper windows 106 and 108 formed in wall 110 on at least one side ofsleeve 100 for engagement by a removal tool to remove sleeve 100. Thesleeve 100 also includes lower elongated visualization window 112centered about the longitudinal axis L with an elongated slot 111extending proximally window 112. Window 112 provides the surgeon withthe ability to visualize the instruments inserted in guide sleeve 100 aswell as the openings in the disc space and vertebral bodies, withoutentirely removing instrumentation from guide sleeve 100. The reducewidth of sleeve 100 allows the use of one window 112 for visualizationof implant insertion into its respective bilateral location in the discspace, and separate windows along each insertion path are not necessary.However, it should be understood that any number of visualizationwindows and configurations thereof are contemplated herein, such asthose described in the '917 patent application. The present inventionalso contemplates that covers may be used for visualization windows, asdescribed in greater detail in the '917 patent application.

At proximal end 102 is provided a flange ring 155. Flange ring 155strengthens sleeve 100 and provides a load transfer member to facilitatetransfer of a driving force to sleeve 100, as described more fullybelow. Adjacent distal end 104, the material thickness along theexterior outer edge of wall 110 is reduced in order to provide a reducedthickness wall portion 114 and an opposite reduced thickness wallportion (not shown). The reduced thickness wall portions define asmaller cross-sectional area for the sleeve 100 as well as a reducedwidth extending transverse to the longitudinal axis L. The reducedcross-sectional area and smaller width of guide sleeve 100 reduces theamount of vasculature and neural tissue retraction adjacent the discspace that would otherwise be required to place a similarly sized guidesleeve without the width reduction.

Distal end 104 includes a pair of flanges 118 and 120 extending fromwall 110 on opposite sides of working channel 130. Flanges 118 and 120are configured to extend partially into the disc space. Flanges 118, 120are each formed by and are an extension of the corresponding reducedthickness wall portions 114 described above. In a preferred embodiment,flanges 118 and 120 do not provide distraction of the disc space but areprimarily provided to protect surrounding vessels and neurologicalstructures from damage during the procedures. Since the lateral flangesdo not provide structural support for distraction, the materialthickness of the flanges and adjacent side walls may be reduced.Additionally, distal end 104 includes spikes 122, 124, positionedbetween flanges 118, 120 and a third spike 126 and a fourth spike 128positioned opposite spikes 122, 124 between flanges 118, 120 as shown inFIG. 7. These spikes may be urged into the bone of the adjacentvertebral bodies to hold guide sleeve 100 in a fixed position relativeto the vertebral bodies.

Referring to FIGS. 4 and 5, guide sleeve 100 is shown in front and sideviews, respectively, to further illustrate an additional aspect of theinvention. A proximal end 102 the guide sleeve 100 has a maximum widthW1. At distal end 104 of sleeve 100, wall 110 has a reduced wallthickness at side walls 114 and 113 defining a width W2 that is lessthan width W1. The side walls 113, 114 are preferably not entirely flatand have a slight curvature. Side walls 113, 114 provide a reduction inwall thickness of wall 110 and taper to the full wall thickness of wall110 at the termination of side walls 113 and 114. The reduction in widthof wall 110 decreases the amount of vasculature and neural tissueretraction in the area adjacent the disc space. The desirable reductionin width is accomplished with little reduction in the required strengthof the device since distractors 50, 80 are used to distract and maintainthe distraction of the vertebral bodies instead of the extensions orside flanges 118, 120 of guide sleeve 100.

There are also shown in FIGS. 4 and 9 a first working channel portion107, defined about axis L1, and a second working channel portion 109,defined about axis L2. These working channel portions 107, 109 arepositioned on either side of longitudinal axis L of sleeve 100. There isno wall or other structure separating working channel portions 107 and109. Working channel portion 107 is that portion of working channel 130about axis L1 between longitudinal axis L and inside surface of 116 ofguide sleeve 100. Similarly, working channel portion 109 is that portionof working channel 130 about axis L2 between longitudinal axis L andinside surface 116. Thus, working channel portions 107 and 109 aresubstantially equal in area, and each has a truncated circular shape,with the truncated portions of each working channel 107 and 109positioned adjacent one another.

Referring now to FIG. 6, there is illustrated a distractor/guide sleeveassembly 150 that includes distractors 50 and 80 disposed within workingchannel 130 of guide sleeve 100 in side-by-side relation. Distractors50, 80 reside within sleeve 100 with each distractor substantiallyoccupying all or a portion of a corresponding one of working channelportions 107 and 109 of working channel 130. Each distractor 50, 80extends from proximal end 102 to distal end 104 of the guide sleeve 100.Flange ring 155 is in the form of a flange extending about the proximalend 102 of guide sleeve 100 and contacts a driving cap positioned ondistractors 50, 80 in order to maintain the relative positioning betweensleeve 100 and distractors 50, 80 during insertion of assembly 150.

Referring now to FIG. 7, there is illustrated an end view at distal end104 of the assembly 150 showing distractors 50 and 80 in side-by-siderelation. More particularly, shaft 54 of distractor 50 is receivedwithin concave portion 98 of distractor shaft 84. As also illustrated inthis view, concave portion 96 of distractor tip 86 is coextensive withconcave surface 98 to form a concave surface that extends the length ofthe distractor 80. The concave surface of distractor 80 has a radius ofcurvature R that is preferably about one half the diameter of the cageor implant to be inserted into the disc space. For example, an 18 mmdiameter implant requires use of a distractor 80 having a radius ofcurvature R of about 9 mm.

When distractor 50 is removed from guide sleeve 100, there is defined acylindrical working space through the working channel 130 adjacent andalong the recessed areas of distractor 80. The cylindrical working spaceincludes that portion of the working channel 130 between concavesurfaces 96, 98 and inside wall 116 of the guide sleeve 100. Thus, theworking space occupies substantially all of working channel portion 107,(FIG. 4) and a portion of working channel portion 109. The area of theportion of the working channel portion 109 occupied by the cylindricalworking space is indicated in FIG. 7 by the hatched area A, and ishereinafter referred to as the overlap region. This overlap region Aallows operative procedures to be performed in the working spaceadjacent the distractor 80 using conventionally sized tools andimplements while providing a guide sleeve 100 of reduced overall width.The amount of width reduction achieved is approximately the maximumwidth of overlap region A. It should be understood that shaft 84 neednot have a recessed area to provide a cylindrical working space in thedisc space, but rather can be provided with a reduced diameter or sizethat maintains access to the overlap region A in the disc space.

In FIG. 8 there is shown a top view of the guide sleeve assembly 150,looking down on proximal ends 53, 83 of the distractors 50, 80 and theproximal end 102 of guide sleeve 100. In one embodiment, there isprovided adjacent proximal end 53 of distractor 50 a locking segment 140formed with and extending from the distractor shaft 54. Locking segment140 has a first projection 142 and a second projection 144. First andsecond projections 142, 144 are received within corresponding notches146, 148 defined in concave surface 98 of shaft 84 of distractor 80 toprevent rotation of distractors 50 and 80 with respect to one another.The present invention also contemplates other mechanisms for engagingdistractors 50 and 80 to prevent rotation relative to one another. Forexample, the above described distractor clip 75 can be used to couplethe distractors 50, 80 together. Moreover, it is contemplated that thedistractors 50, 80 may be inserted without any locking mechanism.

The present invention contemplates that access to the disc space hasheretofore been provided by known surgical techniques and therefore willnot be further described herein. The use of intraoperative templates forproviding access to the disc space is known in the art. One example of aprocedure for gaining access to the disc space is disclosed in the '917patent application. Another reference including techniques for templatepositioning and disc space distraction using a starter distractor toinitially distract the disc space is the surgical technique brochureentitled Reduced Profile Instrumentation published in 1999 by SofamorDanek, said brochure being incorporated by reference herein in itsentirety (hereinafter the Danek brochure.) The present invention alsocontemplates the use and application of other procedures for gainingaccess to the disc space in conjunction with the procedures andinstruments discussed below as would occur to those skilled in the art.The templates contemplated herein define the area necessary forplacement of implants and instruments having a specific configurationand size. While in a preferred embodiment, templates are provided forcylindrical implants having diameters ranging from 16 mm to 24 mm, it iscontemplated that other diameters of implant and templates for usetherewith may be used and other shapes, such as, but without limitation,squares and rectangles.

Access to an anterior portion of the spinal column is achieved by knownmethods. Blood vessels, particularly the aorta, vena cava, and branchesthereof are mobilized to provide space for bilateral implant placement.The template is inserted into the body and advanced until the pins aredisposed adjacent a disc space. The circumference of the template isselected to correspond to the circumference needed for bilateralplacement of a pair of implants. More specifically, the area of thetemplate closely approximates the area needed for placement of the guidesleeve disclosed herein, such as that shown in FIG. 7. It iscontemplated that a guide sleeve 100 need not necessarily be used, andtissue to the surgical site is retracted by other means while the discspace is distracted by distractors 50 and 80. The surgical proceduresare then performed in the working space defined by the distractors 50,80 as discussed below without use of a guide sleeve.

Referring to FIG. 9, a cross section through guide sleeve 100, withdistractors 50, 80 removed for clarity, is provided. Sleeve 100 isinserted into a disc space D between two adjacent vertebra V1 and V2.Disposed adjacent guide sleeve 100 are vessels 560 and 562 graphicallyrepresenting portions of the aorta or vena cava. Referring to FIG. 10, across-section through line 10-10 of FIG. 9, sleeve 100, flanges 118, 120on guide sleeve 100 extend into the disc space where the surgicalprocedures are being performed. Flanges 118, 120 and sleeve 100 inhibitcontact between vessels and tissue surrounding the disc space and thetools used during the surgical procedure. Spikes 122, 124, 126, and 128may be inserted into the bone of the corresponding vertebral body V1,V2.

Various tools and implements are usable with guide sleeve 100 anddistractors 50, 80 disclosed herein and also within the working spacesdefined by the working channel 130 of guide sleeve 100. Several of thesetools are disclosed in the Danek brochure and in the '917 patentapplication, while other tools are known to those skilled in the art towhich the present invention relates.

In accordance with a preferred method of using the apparatus of thepresent invention, reference will now be made to FIGS. 11 through 22. InFIG. 11, the sleeve assembly is assembled and prepared for insertionthrough the skin and to the disc space. Distractor driver cap 250 ofFIGS. 11 a and 11 b is positioned on proximal end 53, 83 of distractors50, 80. Driver cap 250 includes a body 252 having T-shaped slots 253 and254 configured to receive flanged posts 53 a and 83 a of distractors 50and 80, respectively. Opposite slots 253, 254 are windows 256 and 257.Preferably, the flanged portion of posts 53 a and 83 a extend into acorresponding one of the windows 256 and 257 and also into acorresponding one of the upper portions 253 a and 254 a of slots 253 and254 to secure driver cap 250 to distractors 50, 80.

In use, distractor cap 250 contacts flange ring 155 with distractors 50,80 in sleeve 100 such that distractor tips 56, 86 can be driven into thedisc space while flanges 118, 120 remain positioned outside the discspace. The driving force applied to distractor cap 250 is transmitted toflange ring 155, and drives sleeve 100 towards the disc space along withdistractors 50, 80. Alternatively, if distractors 50, 80 are notpositioned in guide sleeve 100, distractor cap 250 is secured toproximal ends 53, 83 and distractor tips 56, 86 are driven into the discspace. Distractor cap 250 is then removed and sleeve 100 placed over theinserted distractors 50, 80 and the procedure continues as discussedbelow. In this alternate technique, clip 75 may be used to coupledistractors 50, 80 together during insertion. In a further variation,alternating insertion of distractors 50, 80 is not precluded by thepresent invention. However, insertion of distractors 50, 80 into thedisc space simultaneously enables the surgeon maintain the positioningof distractors 50, 80 and control the depth of insertion of distractortips 56, 86 with respect to one another.

In FIG. 12 a, an impactor cap 160 is disposed about proximal end 102 ofsleeve 100 over flange ring 155. Sleeve 100 is now relatively free tomove with respect to distractors 50, 80. A driving force is applied toimpactor cap 160 to drive sleeve 100 towards the disc space and positionflanges 118 and 120 therein adjacent the distractor tips 56, 86 alreadypositioned into the disc space as shown in FIG. 12 b. Preferably,flanges 118 and 120 do not distract the disc space and prevent migrationof tissue into the working space when distractor 50, 80 is removed fromsleeve 100.

As shown in greater detail and enlarged FIG. 13, impactor cap 160 ispositioned around and contacts the flange ring 155. Flange ring 155 ispreferably of uniform size and shape for various sized guide sleeves100, thus providing a modular attachment to each of the various sizedguide sleeves for a single impactor cap 160. Impactor cap 160 has ahollow interior 161 for receiving proximal ends 53, 83. Hollow interior161 has a depth d sufficient to allow movement of guide sleeve 100 intothe disc space while the position of distractors 50, 80 is maintained.

In FIG. 14, a slap hammer 165 is engaged to distractor 50 in order towithdrawal distractor 50 from the disc space. In FIG. 15 a thedistractor 50 is removed from the working channel 130 of sleeve 110using the slap hammer 165. The distractor tip 86 of concave distractor80 remains disposed in the disc space to maintain the disc spacedistraction height during subsequent operative steps. In an alternateembodiment, it is contemplated that shaft 84 of distractor 80 isremovably connected to tip 86, in which case the shaft may be withdrawnwhile leaving tip 86 in place. In a further embodiment, shaft 84 has areduced size to accommodate insertion and rotation of devices intooverlap region A of the disc space. With a removable or smaller diametershaft, only tip 86 requires a recessed area.

In FIG. 15 b, the withdrawn distractor 50 leaves a working spacecomprised of working channel portion 109 and an overlap portion,indicated by hatched area A. Thus, the concave surfaces 96, 98 ofdistractor 80 and inside surface 116 of sleeve 110 define asubstantially cylindrical working space for completion of furtheroperative procedures as described further below. The working spacedefines a substantially circular cross section along guide sleeve 100that is adapted for receiving surgical tools therethrough to prepare thedisc space for insertion of an implant. The overlapping configuration ofdistractors 50, 80 provides a reduced overall width for guide sleeve100.

In FIGS. 16 a-16 b, there is shown a reamer 170 disposed through guidesleeve 110. A cutting head 171 has cutting edges as known in the art toream the disc space. As shown in FIG. 16 b, reamer 170 is positionedwithin the working space adjacent distractor 80, while distractor tip 86maintains the disc space distraction. Concave surface 98 of shaft 84 ofdistractor 80 and the inside surface 116 of sleeve 110 acts as a guidefor insertion and/or withdrawal of reamer 170. The depth of reaming canbe controlled with a depth stop 172 and verified via fluoroscopy

In FIGS. 17 a-17 c, the reamer 170 is withdrawn and replaced by atapping tool 175 with a head 176 to prepare the space for a threadedimplant. As shown in FIGS. 17 b and 17 c, tapping tool 175 is positionedwithin the working space adjacent the concave distractor 80, whiledistractor tip 86 maintains the disc space distraction. The concavesurface 98 of shaft 84 of distractor 80 and inside surface 116 of sleeve110 acts as a guide for insertion of tapping tool 175. Tapping tool 175has a depth stop 178 to control the tapping depth in the disc space.Depth and sagittal alignment can also be verified via fluoroscopy duringtapping.

In FIGS. 18 a-18 c, the tapping tool 175 is withdrawn and replaced by animplant insertion device 190 with a threaded implant 200 engaged on adistal end thereof. Threaded implant 200 and insertion device 190 may beany one of the types and configuration disclosed in a first pending PCTApplication No. PCT/US00/00590 filed on Jan. 11, 2000 and a second PCTApplication No. PCT/US00/00604, also filed Jan. 11, 2000; each claimingpriority to U.S. Provisional Application No. 60/115,388, filed Jan. 11,1999, each of said above referenced PCT applications being incorporatedby reference herein in its entirety. Further, the implants of thepresent invention may be any other known implant and insertion device,so long as at least one implant has at least one recessed side wall. Theimplants may be formed of any biocompatible material. Concave surface 98of shaft 84 of distractor 80 and inside surface 116 of sleeve 110 actsas a guide for insertion of the implant into the disc space.

Inserter 190 includes a thumbscrew 191 having a threaded shaft (notshown) extending through inserter 190 to couple implant 200 thereto viaan internally threaded opening in a slotted end 201 (FIG. 19) of implant200. T-handle 192 is used to rotate implant 200 and thread it into thedisc space, as shown in the enlarged view of FIG. 18 b. As shown moreclearly in the enlarged view of FIG. 18 c, implant 200 is inserted sothat a concave face 202 is disposed toward concave surface 96 ofdistractor 80. This positioning of concave face 202 can be confirmed byproviding alignment markings on insertion device 190 and sleeve 100.Further, insertion device 190 includes countersink marking 193 toprovide an indication of the countersink of implant 200 into the discspace. To facilitate implant rotation, inserter 190 can be provided witha movable slide at its distal end that occupies the recessed area ofconcave surface 202 providing a round construct for threading. Whileimplant 200 is threaded into place, distractor tip 86 maintains the discspace distraction.

In FIGS. 19 a-19 b, when implant 200 is placed in the desired position,and implant inserter 190 is removed from guide sleeve 100, distractortip 86 is withdrawn from the disc space. Preferably, a slap hammer 165is engaged to distractor 80 in order to withdraw distractor tip 86 fromthe disc space and distractor 80 from guide sleeve 100. As shown inFIGS. 19 b-19 c, distractor 80 is removed from working channel 130 ofsleeve 110. Implant 200 remains disposed in the disc space to maintainthe disc space distraction height during subsequent operative steps. Thewithdrawn distractor 80 leaves a working space comprised of workingchannel portion 107 and an overlap region A. Thus, concave surface 202of implant 200 and inside surface 116 of sleeve 110 define a cylindricalworking space in the disc space for further procedures as describedbelow. The working space defines a circular cross section that isadapted for receiving conventionally sized surgical tools to prepare thedisc space for insertion of a second implant adjacent implant 200, whileproviding a reduced overall width.

In FIGS. 20 a-20 b, the above described reamer 170 is disposed throughguide sleeve 110. Cutting head 171 has threads as known in the art toream the disc space. As shown in FIG. 20 b, reamer 170 is positionedwithin the working space adjacent the concave surface 201 of implant200, while implant 200 maintains the disc space distraction. The concavesurface 201 of implant 200 and inside surface 116 of sleeve 110 acts asa guide for insertion and operation of reamer 170.

In FIGS. 21 a-21 c, reamer 170 is withdrawn and replaced by theabove-described tapping tool 175 with head 176 to prepare the space fora second threaded implant. As shown in FIGS. 21 b and 21 c, head 176 oftapping tool 175 is positioned within the working space adjacent concavesurface 201 of implant 200, while implant 200 maintains the disc spacedistraction. The concave surface 201 and inside surface 116 of sleeve110 acts as a guide for insertion of tapping tool 175.

In FIGS. 22 a-22 c, the tapping tool is withdrawn and replaced by theabove described implant insertion device 190, with a threaded implant210 engaged on a distal end thereof. Threaded implant 210 may eitherhave a circular cross-section, such as that shown in solid lines inenlarged FIGS. 22 b and 22 c, or have a cross-section identical toimplant 200 with a concave surface 202 as shown in hidden lines. Ineither event, concave surface 201 of implant 200 acts as a guide forthreading of implant 210 into the disc space.

If an implant like that of implant 200 is used, it is preferred toposition implant 210 so that its concave surface 212′ is disposedtowards concave surface 202 of implant 200, forming a cavity 215′therebetween as indicated in dashed lines in FIG. 22 c. The cavity maythen be packed with bone growth promoting material. T-handle 192 is usedto rotate implant 210 and thread it into the disc space, as shown inFIG. 22 b, adjacent to implant 200. If a circular implant similar tothat shown in FIG. 22 c is used, implant 210 is nested within concavesurface 201 of implant 200. Bone growth material can be placed in cavity204 of implant 200 and in cavity 213 of implant 210.

The present invention further contemplates instruments and methodsparticularly suited for inserting threaded fusion devices into a discspace between vertebrae from an anterior approach to the lumbar regionof the spine. It is further contemplated that these threaded devices canbe self-tapping and tapered to establish lordosis between the vertebralendplates when inserted in the disc space therebetween. Examples of suchcages are provided in U.S. Pat. Nos. 5,669,909 and 5,782,919, each ofwhich is incorporated herein by reference in its entirety. While theinstruments and methods described below are contemplated for use withtapered, threaded fusion devices and for use in an anterior approach tothe lumbar region of the spine, aspects of the instruments and methodsmay also have application in other approaches to the spine and in theinsertion of other types and shapes of implants into the disc space.

Referring now to FIGS. 23 a-23 c, there is shown another embodiment of aconvex or first disc space distractor 350 that is, except as describedhereinbelow, similar in many respects to first distractor 50 of FIGS. 1a-1 c. Distractor 350 includes a proximal end 353, a shaft 354 extendingalong longitudinal axis μl, and a distractor tip 356 at the distal endof shaft 354. Proximal end 353 includes a flanged post 353 a having aproximal flange 355 a on the end of the post defining a lip 365 athereabout. A hole 367 a is provided in the proximal face of flange 355a and configured to attach distractor 350 to conventional tools such asa distractor puller.

In the illustrated embodiment, shaft 354 has a hollow interior 357 toreduce its weight; however, the present invention also contemplates asolid shaft 354. Also, while an integral shaft and tip are shown,distractor tip 356 may be removably attached to shaft 354. Distractortip 356 can be provided with a rounded leading edge 362 that extendsbetween a medial side 358 and an opposite lateral side 359 of distractor350. Preferably, for reasons described further below, the transitionbetween leading end 362 and medial side 358 is relatively abrupt suchthat leading edge 362 remains extended to its most distal-most point atthe transition therebetween. A gradual arcuate transition is providedbetween lateral side 359 and leading edge 362. Distractor tip 356 alsoincludes opposing vertebral contacting surfaces 360 and 361, which caneach include serrations 372 to engage the vertebral endplates and resistmovement of distractor tip 356 in the disc space. Distractor tip 356 isdesigned such that it can be inserted in a disc space to establish adistraction height 372 (see FIG. 23 a) between the vertebral endplates.Distractor tip 356 is preferably made from aluminum or other radiolucentmaterial, and includes a radiographic marker 351 to allow the surgeon todetermine and monitor distractor tip 356 during insertion into the discspace. Shaft 354 and flanged post 353 a, and in the alternative tip 356,can be made from stainless steel or other acceptable material forsurgical instruments.

Distractor 350 further includes a projection 374 that is cylindricallyshaped, although other shapes are also contemplated, that extendsmedially from medial side 358. The significance of projection 374 willbe discussed further below. A color-coded marker 352 is provided inshaft 354 to give the surgeon an indication of the size of distractortip 356.

Referring now to FIGS. 24 a-24 c, there is shown a second disc spacedistractor 380 that is, except as described hereinbelow, similar in manyrespects to second distractor 80 of FIGS. 2 a-2 c. Distractor 380includes a proximal end 383, a shaft 384 extending along axis B1, and adistractor tip 386 at the distal end of shaft 384. Proximal end 383includes a flanged post 383 a having a proximal flange 385 a on the endof the post defining a lip 395 a thereabout. A hole 397 a is provided inthe proximal face of flange 385 a that is configured to attachdistractor 350 to conventional tools such as a distractor puller.

In the illustrated embodiment, shaft 384 has a hollow interior 387 toreduce its weight; however, the present invention also contemplates asolid shaft 384. Also, while an integral shaft and tip are shown,distractor tip 386 may be removably attached to shaft 384. Distractortip 386 can be provided with a rounded leading edge 392 that extendsbetween a medial side 388 and an opposite lateral side 389 of distractor380. Preferably, for reasons described further below, the transitionbetween leading end 392 and medial side 388 is relatively abrupt suchthat leading edge 382 remains extended to its most distal-most point atthe transition therebetween. A gradual arcuate transition is providedbetween lateral side 389 and leading edge 392. Distractor tip 386 alsoincludes opposing vertebral endplate contacting surfaces 390 and 391,which can include serrations 392 to engage the vertebral endplates andresist movement of distractor tip 386 in the disc space. Distractor tip386 is designed such that it can be inserted in a disc space toestablish a distraction height 372′ (see FIG. 24 a) between thevertebral endplates. Distractor tip 386 is preferably made from aluminumor other radiolucent material, and includes a radiographic marker 381 toallow the surgeon to determine and monitor distractor tip 386 duringinsertion into the disc space. Shaft 384 and proximal end 386, and inthe alternative tip 386, can be made from stainless steel or otheracceptable material for surgical instruments.

Extending along medial side 388 of distractor 380 extending from leadingedge 392 to proximal flange 385 is a recessed area defined by ascalloped or concave surface 394. In the illustrated embodiment, concavesurface 394 has a window 399 formed therein communicating with thehollow interior 387 of shaft 384. In a manner similar to that discussedabove with respect to distractors 50 and 80, concave surface 394 mateswith the convex medial surface 358 of first distractor 350 whendistractors 350 and 380 are disposed with medial sides 358 and 388 inside-by-side relation as shown in FIGS. 25 a and 25 b. Thus distractors350, 380 form an overall reduced width for the adjacent distractors. Theleading ends 362, 392 form a single blunt leading end for the adjacentdistractors 350, 380 when assembled.

To aid in distractor insertion, distractor 380 includes a notch 396formed in the adjacent the proximal end of shaft 384 sized to receiveprojection 374 as shown in FIGS. 25 a and 25 b. Notch 396 has aproximally facing opening 398 that allows projection 374 to betop-loaded therein from the proximal direction and withdrawn therefromin the distal direction when distractors 350, 380 are adjacent oneanother. Projection 374 and notch 396 resist rotation of distractors350, 380 relative to one another and maintain the relative positioningof distractors 350, 380 during insertion into the disc space.

Specifically, but without limitation, the distractor tips 356, 386 maybe formed with heights 372, 372′ ranging from 6 mm to 24 mm. Preferably,the height of the next sized distractor increases or decreases in 2 mmincrements. Other variations and may be provided as long as the workingdistractor height provided approximates the disc height in a normalspine and accommodates insertion of an implant into the disc space asdescribed herein.

Referring now to FIGS. 26 a-26 c, there is shown a guide sleeve 400 thatreceives distractors 350, 380 described above. Guide sleeve 400 issimilar to guide sleeve 100 and can also receive distractors 50, 80.Guide sleeve 400 has a wall defining a working channel 430 having afigure eight shaped cross-section. Working channel 430 extends in asubstantially unobstructed manner from a proximal end 402 to a distalend 404. Distal end 404 is concave to match the contour of the anterioraspect of the vertebral bodies against which it is positioned. Sleeve400 also includes an elongated visualization window 412 centered aboutthe longitudinal axis L6 with a tapered portion 411 extending proximallyfrom window 412 and blending into wall 410. As discussed above withrespect to window 112 of guide sleeve 100, window 412 provides thesurgeon with the ability to visualize the instruments inserted inworking channel 430 of guide sleeve 400 as well as the openings in thedisc space and vertebral bodies.

Adjacent distal end 404, the material thickness along the lateral edgeportions wall 410 is reduced in order to provide a reduced thicknesswall portion 414 and an opposite reduced thickness wall portion 415 in amanner similar to that discussed above with respect to guide sleeve 100.Guide sleeve 400 includes a pair of flanges 418 and 420 extending fromdistal end 404 on opposite sides of working channel 430. Flanges 418 and420 are configured to extend partially into the disc space, and are eachan extension of the corresponding reduced thickness wall portions 414,415 described above. Preferably, as discussed above with respect toguide sleeve 100 and flanges 118 and 120, flanges 418 and 420 do notprovide distraction of the disc space but are primarily provided toprotect surrounding vessels and neurological structures from damageduring the procedures. Since flanges 418, 420 do not provide structuralsupport for distraction, the material thickness of the flanges andadjacent side walls may be reduced.

Guide sleeve 400 also includes a first working channel portion 407,defined about axis L7, and a second working channel portion 409, definedabout axis L8. These working channel portions 407, 409 are positioned oneither side of longitudinal axis L6 of sleeve 400. There is no wall orother structure separating working channel portions 407 and 409. Asdiscussed above with respect to guide sleeve 100 and working channelportions 107, 109, working channel portions 407 and 409 aresubstantially equal in area, and each has a truncated circular shape,with the truncated portions of each working channel 407 and 409positioned adjacent one another.

A sleeve cap 455 is provided at proximal end 402 and is welded,integrally formed with, or otherwise attached to wall 410 of sleeve 400.Sleeve cap 455 includes a proximal groove 406 formed therein adjacentproximal end 402 that defines a proximal end ring 407 around sleeve 400.Sleeve cap 455 also includes a circumferential ring member 408 extendingtherearound and positioned distally of proximal groove 406. As describedfurther below, sleeve cap 455 facilitates connection of driving caps tosleeve 400 and the assembly of distractors 350, 380 with sleeve 400.

A side-loading distractor driver cap 550 is shown in FIG. 27 a-27 d.Distractor driver cap 550 includes a body 552 having an upper portion554 and a lower attaching portion 556. Attaching portion 556 has a sideopening 558 that communicates with a distractor securing portion 560 anda sleeve securing portion 562 provided in the interior of attachingportion 556. Distractor securing portion 560 and sleeve securing portion562 are configured to allow distractor driver cap 550 to be side-loadedthrough side opening 558 onto the distractor assembly 450 (FIG. 28) toassemble distractors 350, 380 and guide sleeve 400.

Distractor securing portion 560 includes a distractor slot 564 having afirst ledge 568 therearound formed by upper extension 567. Distractorslot 564 is configured to receive proximal flanges 355 a and 385 a offlange posts 353 a and 383 a, respectively, of distractors 350, 380 whenpositioned together as shown in FIG. 25 b. Lips 365 a and 395 a offlange posts 353 a and 383 a, respectively, contact first ledge 568formed around distractor slot 564. Sleeve securing portion 562 includesa sleeve slot 566 having a second ledge 570 therearound formed by abottom extension 572. Sleeve slot 566 is configured to receive proximalend ring 407 of sleeve 400 with bottom extension 572 positioned inproximal groove 406 when distractors 350, 380 are inserted into sleeve400 as shown in FIG. 28. Distractor driver cap 550 secures distractors350, 380 together and also secures distractors 350, 380 relative toguide sleeve 400 forming distractor assembly 450. This allows thesurgeon to insert distractor assembly 450 through skin and tissue to thedisc space without distractors 350, 380 and sleeve 400 moving relativeto one another. Preferably, distractor tips 356, 386 extend distallybeyond the flanges 418, 420 to the distractor tips can be inserted intothe disc space without inserting flanges 418, 420 into the disc space.

Referring to FIG. 27 c, upper portion 554 is preferably solid to delivera driving force to the proximal flanges 355 a, 385 a of distractors 350,380 respectively. To ensure side-loading distractor driver cap 550 isproperly positioned on distractors 350, 380, a well 574 is provided inupper portion 554 in communication with distractor securing portion 560.A spring-biased plunger 576 has a nub 578 extending into distractorsecuring portion 560. When one of the proximal flanges 355 a, 385 acontacts nub 578, spring 580 compresses and plunger 576 is pushed intowell 574. Depending on the side from which distractor driver cap 550 isloaded, one of the holes 367 a, 397 a will align with nub 578 and spring580 pushes nub 578 into the corresponding hole 567 a, 597 a. Thiscreates a clicking sound and an audible indication that distractordriver cap 550 is properly seated on the distractors 350, 380.

In FIG. 29, there is shown a reamer 470 positionable through a selectedone of the working portions 407, 409 of guide sleeve 400. Reamer 470includes a cutting head 471 attached to the distal end of a shaft 474.Cutting head 471 has cutting blades 476 extending in a helical patternfrom a body 478 configured to ream a cylindrical hole in a disc space.Body 478 has elongated openings 480 formed therethrough along eachcutting blade 476 that communicate with a hollow interior defined bybody 478. A port 482 in shaft 474 provides access to the interior ofbody 478 for material removal therefrom. An opening (not shown) in thedistal end of body 478 can also be provided for this purpose. The depthof reaming can be monitored and controlled with a depth stop, such asdepth stop 172 of FIG. 16 a, and depth markings 484 on shaft 474. Aconnector 486, such as a Hudson type connector, is provided at theproximal end of shaft 474 for connection with a T-handle driving tool.

Referring now to FIGS. 30 a-30 b, a reamer plug 600 is illustrated.Reamer plug 600 has a shaft 602 and a plug 604 at the distal end ofshaft 602. A handle 606 is provided at the proximal end of shaft 602.Shaft 602 is generally cylindrical but includes a concave surface 612extending along a medial side thereof to accommodate rotation of a tooltherebeside. Handle 606 has a scalloped portion 608 connected to shaft602. Scalloped portion 608 has a cavity 614 formed around shaft 602 thatreceives the proximal end of guide sleeve 400 when reamer plug 600 isfully inserted therein to clock shaft 604 against the sidewall of guidesleeve 400. Handle 606 further includes a laterally extending portion610 that extends away from shaft 602 opposite concave surface 612 thatfacilitates insertion and removal of plug 604 into the reamed disc spacelocation. The scalloped portion 608 and laterally extending portion 610provide clear access to one of the working channel portions 407, 409 ofguide sleeve 400 when reamer plug 600 is disposed in the other workingchannel portion 407, 409.

Referring now to FIG. 31, there is shown an implant adjuster 620.Implant adjuster 620 has a shaft 622 extending between a proximal end624 and a distal end 626. As discussed further below, distal end 626 hasan implant engaging portion 628 configured to engage an implant that hasbeen implanted into the disc space to provide adjustment of the finalalignment of the implant. Proximal end 624 can be provided with aHudson-type connector connectable to a T-handle or the like to apply arotational force to the implant through implant adjuster 600.

Referring now FIGS. 32 a-32 b, there is illustrated an implant holder650. Implant holder 650 includes a shaft 652 extending between aproximal 654 and a distal end 656. Shaft 652 includes a threaded portion664 adjacent proximal end 654. Distal end 656 includes an implantengaging portion having a pair of fingers 658 extending from an endsection 668. A shoulder 666 is provided between a tapered section 662and end section 668. Projections 672 extend distally from a distal endwall of end section 668. A slit 670 extends between the projections 672proximally along the center axis C of implant holder 650 for a distanced, biasing implant holder 650 to a position that is disengaged with theimplant. Flats 674 are provided adjacent the proximal end of shaft 652to provide an indication of the orientation of fingers 658.

Referring now to FIG. 33, an implant driver sleeve 680 is provided.Driver sleeve 680 includes a cylindrical member 682 having a hollowinterior sized to receive implant holder 650 therethrough. Cylindricalmember 682 includes threads (not shown) formed in its hollow interiorconfigured to mate with threads 664 on implant holder 650. Cylindricalmember 682 has a proximal end 684 with a hex nut 686 secured thereto.Cylindrical member 682 further includes a distal end 688 having abushing 690 secured thereto. It is preferred that bushing 690 is madefrom a lubricious plastic material such as DELRIN and is press fit ontodistal end 688. In FIG. 34, a wrench 695 is provided with a handle 696and an open-sided hex driving head 697 sized to engage hex nut 686 ofimplant driver sleeve 680. Implant holder 650 has a sufficient lengthsuch that distal end 656 extends distally from distal end 688 of driversleeve 680, and proximal end 654 of implant holder 650 extendsproximally from proximal end 684 of driver sleeve 680.

To secure an implant 800 to implant holder 650 as shown in FIGS. 43 a-43b, implant holder 650 is placed through driver sleeve 680 and securedthereto by partially mating the proximal end of threads 664 onto thedistal end of the inner thread of cylindrical member 682. A T-handle 674is secured to a connector at proximal end 654 of implant holder 650.Implant 800 is held in position by a vise and the implant can bepre-packed with bone growth material through a proximal end opening ofthe implant. Implant holder 650 is then positioned with fingers 658around implant 800, and projections 672 can be received in the endopening of the implant. Preferably, fingers 658 are configured to matewith flats or other surfaces provided on the sidewalls of implant 800.Implant holder 650 is threaded proximally with respect to driver sleeve680 so that bushing 690 contacts tapered portion 662, and taperedportion 662 is pulled proximally into the distal end opening of driversleeve 680. Implant holder 650 can be held to prevent its rotation withhandle 674 while driver sleeve 650 is rotated with wrench 695. The forceexerted on tapered portion 662 of implant holder 650 moves implantholder 650 to an engaged position with the implant 800 by causing slit670 to narrow and fingers 658 to be pushed towards one another to firmlygrip implant 800 therebetween. Plastic bushing 690 prevents jamming ofimplant holder 650 with driver sleeve 680, and also facilitatesdisassembly of outer sleeve 680 from implant holder 650 to releaseimplant 800 after implant 800 is inserted in the disc space.

Referring now to FIGS. 35 a to 45, an example of a preferred surgicaltechnique employing the instruments of FIGS. 23 a-34 in an anteriorapproach to the spine to insert a first implant 800 and a second implant800′ bi-laterally in the disc space (as shown in FIG. 45) will now bedescribed. It will be understood however, that the instruments of FIGS.23 a-34 can also have application in other approaches to the spine andwith other types of implants mentioned herein.

Referring now to FIGS. 35 a-35 c, the disc space between the L5 and S1level of the spine has been accessed through an anterior exposure. Themiddle sacral artery is typically ligated and divided with thisapproach. It is also contemplated that the L4-L5 level of the spinecould be accessed with the iliolumbar and segmental vessels identifiedand ligated if necessary. The center of the disc space is identified andmarked with a template shaft 700 and centering pin 705. Accurateidentification of the midline can be made with the assistance ofanterior/posterior and lateral fluoroscopy. Marks M are made at themidline both cephalad and caudal to centering pin 705 on the vertebralbodies.

The centering pin 705 is then removed, and as shown in FIG. 36 a anappropriate sized template 710 is attached to shaft 700 and positionedso that notch 712 aligns with marks M. The lateral margins of the blockdiscectomy are marked by sharply incising the annulus with cuttinginstrument 715. As shown in FIGS. 36 b and 36 c, template 710 is removedand an en bloc discectomy is typically performed to create an opening Othat provides adequate space for insertion of distractors 350, 380. Adisc material removal instrument 720, such as a pituitary rongeur, canbe used to remove the nucleus pulposous to provide room in the discspace for the distractors and the implants 800. The anterior osteophyteson the vertebral bodies can also be removed to ensure accurate seatingof the distal end of guide sleeve 400 against the vertebral bodies.Curettes can be used to remove the cartilaginous endplates. Thediscectomy is performed under direct vision, and lateral fluoroscopy canbe used to confirm the extent of disc removal in the posterior portionof the disc space. The lateral margins of the discectomy should not beexceeded so that the anterolateral annulus remains intact to enhance thestability of the construct.

If necessary, sequential distraction of the disc space can be carriedout using starter distractor set 725 as shown in FIG. 37. Starterdistractor set 725 includes a number of distractor tips of increasingheight 726 a, 726 b, 726 c, 726 d attachable to distractor handle 728.If necessary, the distractor tips are sequentially driven into the discspace to develop the disc space height prior to insertion of distractorassembly 450.

Referring now to FIG. 38, distractor assembly 450 is then assembled withdistractor driver cap 550 as discussed above. The distractor tips ofdistractors 350, 380 are then inserted into opening O with care taken toensure distractor assembly 450 is placed at midline M. Distractor drivercap 550 is then impacted until the distractor tips are fully seated inthe disc space. The radiographic markers in the tips can be used toverify positioning during seating. Distractor assembly 450 should remainparallel to the endplates during seating, and the intact anterolateralannulus will act to center the distractor assembly 450 and resistlateral migration during impaction. The distractor driver cap 550 isthen removed to de-couple distractors 350, 380 from guide sleeve 400.

Referring now to FIG. 39, an impactor cap 730 is secured to guide sleeve400 and the guide sleeve 400 is impacted until flanges 418 and 420 arefully seated in the disc space and the distal end of sleeve 400 ispositioned against the vertebral bodies while distractors 350, 380remain as positioned in the disc space with distractor driver cap 550.Impactor cap 730 is then removed. As shown in FIG. 40 a, an instrumentremover such as slap hammer 165 is secured to first distractor 350.First distractor 350 is then removed, and a cylindrical working channelis provided through guide sleeve 400 to the disc space along therecessed area defined by concave surface 394 of second distractor 380 asshown in FIGS. 40 b and 40 c.

Referring now to FIGS. 41 a and 41 b, reamer 470 is positioned in theworking channel to ream a cylindrical hole in the disc space at a firstdisc space location to prepare it for insertion of implant 800.Preferably, the reamer 470 creates a hole that is sized to correspond tothe height of the leading end of the implant to be inserted into thedisc space. Reamer 470 is attached to a depth stop, such as the depthstop 172 discussed above, and T-handle 674. The appropriate depth stopsetting is selected based on preoperative templating using axial CT orMR images, and should reflect the length of implant 800 and the desiredcountersink of implant 800 in the disc space. The depth of reaming inthe disc space can be verified with fluoroscopy.

Referring now to FIG. 42 a reaming plug 600 is inserted into the reamedfirst disc space location created with reamer 470. First implant 800 ispreferably not inserted into the first disc space location after thefirst disc space location is reamed. The tapered first implant 800 actsto distract the disc space to establish the lordotic angle between theendplates. Reaming of the second disc space location could beproblematic if first implant 800 was inserted into the first disc spacelocation before the second disc space location is reamed. Thus reamerplug 600 maintains the disc space distraction while distractor 380 isremoved. Reamer 470 is then used to ream a second disc space locationadjacent the first disc space location for insertion of second implant800′. Plug 604 is sized such that sufficient space exists in the discspace for cutting head 471 to rotate with the shaft of reamer 470positioned along concave surface of shaft 602. Handle 606 engages theproximal end of sleeve 400 to clock shaft 602 against the inner side ofthe wall of guide sleeve 400 to keep reamer plug 600 from interferingwith reamer 470 and also from interfering with insertion of secondimplant 800′.

As discussed above, second implant 800′ is engaged to an implantinserter by engaging the implant holder 650 to implant 800′ with driversleeve 680 as shown in FIGS. 43 a and 43 b. As shown in FIGS. 44 a-44 c,second implant 800′ is threaded into the second disc space location withreamer plug 600 inserted at the first disc space location. Secondimplant 800′ preferably includes self-tapping threads, and is tapered toestablish the desired lordotic angle between the endplates. After secondimplant 800′ is inserted into the second disc space location, implantholder 650 and driver sleeve 680 are removed. Reamer plug 600 iswithdrawn from the first disc space location, and first implant 800 isinserted into the first disc space location as shown in FIG. 45 with theimplant inserter. When inserted, implants 800, 800′ preferably arecountersunk 2 to 5 millimeters from the anterior face of the vertebralbodies. If necessary, implant adjuster 620 can be inserted into theproximal end opening of the implants 800, 800′ for alignmentcorrections. Bone growth G material can be placed around the implants800, 800′ in the disc space to facilitate fusion.

While the use of threaded implants has been primarily discussed for usewith the instruments of the present invention, the present inventionlikewise contemplates using push-in type implants and/or expandableimplants in the disc space with the instruments described herein. Also,while it is preferred that the present invention be utilized forinsertion of two implants at bilateral locations within the disc space,insertion of a single implant into the disc space is also contemplated.

Of course, the present invention makes use of depth stops and otherdevices for measuring and controlling the depth of the variousprocedures performed in the disc space. These devices and procedures aremore fully explained in the Danek brochure and in the '917 patentapplication. Additionally, the present invention is not limited to usewith the tools and instruments described above, and guide sleeve 100 anddistractors 50, 80 may be used with other such devices as would normallyoccur to those skilled in the art to which the invention relates.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. A device for inserting a spinal implant into aspinal disc space, comprising: an implant holder engageable to theimplant, the implant holder being biased to a disengaged position andmoveable to an engaged position with the spinal implant, said implantholder including: a shaft having a threaded portion and a taperedportion increasing in size towards a distal end of said shaft; animplant engaging portion at a distal end of said shaft, wherein saidimplant engaging portion includes a distal end section extendingdistally from said tapered portion to a distal end wall, said implantengaging portion further including a pair of projections extendingdistally from said distal end wall with a slit extending through saiddistal end wall separating said pair of projections from one another,said implant engaging portion also including said distal end wallforming a recess between said pair of projections and respective ones ofa pair of fingers, said pair of fingers extending distally from oppositesides of said distal end wall to grasp opposite sides of the spinalimplant in the engaged position when said pair of projections arepositioned in an opening of the spinal implant; and a driver sleevehaving a hollow interior, said driver sleeve being threadingly engagedto said shaft with a plastic bushing on a distal end of said driversleeve in contact with said tapered portion, wherein said driver sleeveincludes a hex nut on a proximal end of said driver sleeve, said implantengaging portion extending distally from said distal end of said driversleeve, wherein said implant holder and said driver sleeve are rotatablerelative to one another to move said implant holder from said disengagedposition to engage the spinal implant.
 2. The device of claim 1, whereinsaid slit extends proximally from said distal end wall along a centeraxis of said shaft.
 3. The device of claim 1, wherein said implantengaging portion includes a shoulder extending outwardly from saidtapered section between said distal end section and said taperedsection.
 4. The device of claim 1, wherein said fingers are configuredto mate with flat sides of the spinal implant.
 5. The device of claim 1,wherein said slit is narrowed as said implant holder is moved to saidengaged position.
 6. The device of claim 1, wherein said shaft includesopposite flats adjacent a proximal end of said shaft to provide anindication of an orientation of said pair of fingers.
 7. The device ofclaim 1, wherein said driver sleeve includes a cylindrical memberextending from said distal end to a proximal end of said driver sleeve.8. A device for inserting a spinal implant into a spinal disc space,comprising: an implant holder engageable to the implant, the implantholder being biased to a disengaged position and moveable to an engagedposition with the spinal implant, said implant holder including: a shafthaving a threaded portion and a tapered portion increasing in sizetowards a distal end of said shaft; an implant engaging portion at adistal end of said shaft, wherein said implant engaging portion includesa distal end section extending distally from said tapered portion to adistal end wall, said implant engaging portion further including a pairof projections extending distally from said distal end wall with a slitextending through said distal end wall separating said pair ofprojections from one another, said implant engaging portion alsoincluding said distal end wall forming a recess between said pair ofprojections and respective ones of a pair of fingers, said pair offingers extending distally from opposite sides of said distal end wallto grasp opposite sides of the spinal implant in the engaged positionwhen said pair of projections are positioned in an opening of the spinalimplant; and a driver sleeve having a hollow interior, said driversleeve being threadingly engaged to said shaft with a lubricious bushingat a distal end of said driver sleeve in contact with said taperedportion, wherein said driver sleeve includes a hex nut on a proximal endof said driver sleeve, said implant engaging portion extending distallyfrom said distal end of said driver sleeve, wherein said implant holderand said driver sleeve are rotatable relative to one another to movesaid implant holder from said disengaged position to engage the spinalimplant.
 9. The device of claim 8, wherein said slit extends proximallyfrom said distal end wall along a center axis of said shaft.
 10. Thedevice of claim 8, wherein said implant engaging portion includes ashoulder extending outwardly from said tapered section between saiddistal end section and said tapered section.
 11. The device of claim 8,wherein said fingers are configured to mate with flat sides of thespinal implant.
 12. The device of claim 8, wherein said slit is narrowedas said implant holder is moved to said engaged position.
 13. The deviceof claim 8, wherein said shaft includes opposite flats adjacent aproximal end of said shaft to provide an indication of an orientation ofsaid pair of fingers.
 14. The device of claim 8, wherein said driversleeve includes a cylindrical member extending from said distal end to aproximal end of said driver sleeve.
 15. The device of claim 8, whereinsaid bushing is plastic.